(1) Field
This application relates to devices and methods for joining bones.
(2) Description of the Related Art
Hammertoe deformity, the most common deformity of the lesser toes, is a flexion deformity of the proximal interphalangeal (PIP) joint of the toe, with hyperextension of the metatarsophalangeal (MTP) and distal interphalangeal (DIP) joints. Progressive PIP joint flexion deformity typically leads to compensatory hyperextension of the MTP and DIP joints. This makes the PIP joint prominent dorsally. Pain occurs due to rubbing of the prominence against the patient's shoe. The deformity is flexible at first but usually becomes fixed over time. When the deformity is flexible, various procedures can be utilized that involve manipulation of the involved tendons. However, when the deformity is fixed, PIP fusion or joint replacement is often required. Implants available for this purpose include the Weil-Carver™ Hammertoe Implant (Biomet®, Inc., Warsaw, Ind.), Flexible Digital Implant (Tornier, Inc. Edina, Minn.), SHIP Implant (Sgarlato Labs, Campbell Calif.), Digital Compression Screw (BioPro®, Port Huron Mich.), Smart Toe™ Intramedullary Memory Implant (Memometal Inc., Memphis Tenn.) and StayFuse™ Intramedullary Fusion Device (Tornier, Inc. Edina, Minn.). The latter three implants are used when fusion is desired, since the other implants allow some flexibility of the joint. With all current implants, placement is critical because, when mounted, there is no adjustability in the angle of flexion between the two cut bones to be joined.
There is thus a need for alternative designs for implants for joining two bone pieces, including implants that fix the two bone pieces, particularly designs that allow adjustment of the angle of flexion between the two bones. The present invention addresses that need.